Semiconductor device

ABSTRACT

An interconnect substrate is placed over a first inductor of a semiconductor chip and a second inductor of another semiconductor chip. The interconnect substrate includes a third inductor and a fourth inductor. The third inductor is located above the first inductor. The distance from the first inductor to the third inductor is longer than the distance from the second inductor to the fourth inductor.

This application is based on Japanese patent application No.2009-102278, the content of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a semiconductor device that is capableof transferring electric signals between two circuits to which electricsignals having different potentials from each other are input.

2. Related Art

To transfer electric signals between two circuits to which electricsignals having different potentials from each other are input, photocouplers are often used. Each photo coupler includes a light emittingelement such as a light emitting diode and a light receiving elementsuch as a photo transistor. The light emitting element converts an inputelectric signal into light, and the light receiving element returns thelight to an electric signal. In this manner, photo couplers transferelectric signals.

However, it is difficult to reduce the size of each photo coupler due tothe existence of the light emitting element and the light receivingelement. Also, where the frequency of electric signals is high, thephoto couplers cannot follow the electric signals. To counter theseproblems, there has been a technique for transmitting electric signalsby inductively coupling two inductors, as disclosed in Japanesetranslation of PCT international application NO. 2001-513276, forexample.

A structure in which pairs of inductors are used when a firstsemiconductor chip on the transmission side and a second semiconductorchip on the reception side are connected to each other through atransmission path is disclosed in Japanese Laid-open patent publicationNO. 2008-113093. More specifically, the transmission line and the firstsemiconductor chip are connected in a noncontact manner byelectromagnetically coupling the pair of inductors on the transmissionside. The transmission line and the second semiconductor chip areconnected in a noncontact manner by electromagnetically coupling thepair of inductors on the reception side.

The present inventor has recognized as follows. Where atransmission-side circuit and a reception-side circuit are connectedthrough an interconnect substrate, the transmission-side circuit and theinterconnect substrate may be connected by a pair of inductors, and theinterconnect substrate and the reception-side circuit may be connectedby a pair of inductors. In such a case, two pairs of inductors are used.Therefore, there is a possibility that signal attenuation occurs whilesignals are being transferred, and the signals cannot be transferredaccurately. To transfer signals accurately, the distance between twoinductors forming the pairs of inductors may be made shorter. However,where the reference voltage of the transmission-side circuit and thereference voltage of the reception-side circuit differ from each other,insulation between the transmission-side circuit and the reception-sidecircuit cannot be secured, if the distance between the two inductorsforming the pairs of inductors is made shorter at each two pairs ofinductors. Therefore, it is difficult to secure insulation between thetransmission-side circuit and the reception-side circuit while signalsare being transferred accurately.

SUMMARY

In one embodiment, there is provided a semiconductor device including:

one or two semiconductor chips that include an interconnect layer; and

an interconnect substrate that is attached to an interconnect layer sideof the one or two semiconductor chips,

wherein the one or two semiconductor chips includes:

a first circuit that generates a signal;

a first inductor that is formed in the interconnect layer and isconnected to the first circuit;

a second circuit that processes the signal; and

a second inductor that is formed in the interconnect layer and isconnected to the second circuit,

the interconnect substrate includes:

a third inductor that is located above the first inductor; and

a fourth inductor that is located above the second inductor and isconnected to the third inductor, and

a distance from the first inductor to the third inductor differs from adistance from the second inductor to the fourth inductor.

According to the embodiment, the distance from the first inductor to thethird inductor differs from the distance from the second inductor to thefourth inductor. The breakdown voltage between the first circuit and thesecond circuit is determined by the sum of the distance from the firstinductor to the third inductor and the distance from the second inductorto the fourth inductor. Therefore, the sum of the distance from thefirst inductor to the third inductor and the distance from the secondinductor to the fourth inductor needs to be equal to or larger than acertain value. When a semiconductor device is designed, the requiredvalue is divided between the distance from the first inductor to thethird inductor and the distance from the second inductor to the fourthinductor. The distance from the first inductor to the third inductor andthe distance from the second inductor to the fourth inductor differ fromeach other, and have appropriate values. With this arrangement, theefficiency in signal transmission from the first circuit to the secondcircuit can be maximized. Accordingly, insulation can be secured betweenthe first circuit and the second circuit while signals are beingtransferred accurately.

According to the embodiment, even where the interconnect substrate andthe first circuit on the transmission side are connected by a pair ofinductors, and the interconnect substrate and the second circuit on thereception side are connected by a pair of inductors, insulation can besecured between the first circuit and the second circuit while signalsare being accurately transferred.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description ofcertain preferred embodiments taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view showing the structure of asemiconductor device according to a first embodiment;

FIG. 2 is a schematic plan view of the semiconductor device shown inFIG. 1;

FIG. 3 is an equivalent circuit diagram of the semiconductor deviceshown in FIG. 1;

FIG. 4 is a cross-sectional view showing the structure of asemiconductor device according to a second embodiment;

FIG. 5 is a schematic plan view of the semiconductor device shown inFIG. 4;

FIG. 6 is a schematic cross-sectional view showing the structure of asemiconductor device according to a third embodiment;

FIG. 7 is a schematic plan view of the semiconductor device shown inFIG. 6;

FIG. 8 is an equivalent circuit diagram of the semiconductor deviceshown in FIG. 6;

FIG. 9 is a schematic cross-sectional view showing the structure of asemiconductor device according to a fourth embodiment; and

FIG. 10 is a schematic plan view of the semiconductor device shown inFIG. 9.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposes.

The following is a description of embodiments of the present invention,with reference to the accompanying drawings. In the drawings, likecomponents are denoted by like reference numerals, and explanation ofthem will not be repeated made in the following description.

First Embodiment

FIG. 1 is a diagram showing the structure of a semiconductor deviceaccording to a first embodiment. FIG. 2 is a schematic plan view of thesemiconductor device shown in FIG. 1. FIG. 1 is a cross-sectional viewof the semiconductor device, taken along the line A-A′ of FIG. 2. Forsimplification of the drawings, the number of windings in each of thelater described first inductor 302 and second inductor 322 in FIG. 1differs from the number of windings shown in FIG. 2. This semiconductordevice includes two semiconductor chips 10 and 20, and an interconnectsubstrate 60. The semiconductor chip 10 includes a multilayerinterconnect 400, and the semiconductor chip 20 includes a multilayerinterconnect 500.

The semiconductor chip 10 includes a first substrate 102, a firstcircuit 100, and a first inductor 302. The first substrate 102 is asemiconductor substrate such as a silicon substrate. The first circuit100 generates signals to be transmitted. The first inductor 302 isformed in the multilayer interconnect 400. The first inductor 302 isconnected to the first circuit 100, and receives the signals generatedby the first circuit 100.

The semiconductor chip 20 includes a second substrate 202, a secondcircuit 200, and the second inductor 322. The second substrate 202 is asemiconductor substrate such as a silicon substrate. The second circuit200 receives and processes the signals generated by the first circuit100. The second inductor 322 is formed in the multilayer interconnect500. The second inductor 322 is connected to the second circuit 200, andtransmits signals to the second circuit 200. The signals to betransmitted are digital signals, for example, but those signals may alsobe analog signals.

The interconnect substrate 60 is placed over the first inductor 302 ofthe semiconductor chip 10 and the second inductor 322 of thesemiconductor chip 20. The interconnect substrate 60 is attached to thesemiconductor chip 10 and the semiconductor chip 20 through an adhesiveagent (not shown), for example. The interconnect substrate 60 includes athird inductor 304 and a fourth inductor 324. The third inductor 304 islocated above the first inductor 302. The fourth inductor 324 is locatedabove the second inductor 322, and is connected to the third inductor304. The distance from the first inductor 302 to the third inductor 304is longer than the distance from the second inductor 322 to the fourthinductor 324. Each of the inductors is a spiral interconnect pattern.

In the example illustrated in FIG. 1, the interconnect substrate 60 is asilicon interposer that is formed with a silicon substrate 602. Theinterconnect substrate 60 may be an interposer or an interconnectsubstrate using a substrate made of resin. Where the interconnectsubstrate 60 is formed with the use of the silicon substrate 602, andthe first substrate 102 and the second substrate 202 are siliconsubstrates, the impurity density in the silicon substrate of theinterconnect substrate 60 is preferably lower than the substrateimpurity density in the first substrate 102 and the substrate impuritydensity in the second substrate 202. With this arrangement, generationof eddy current in the silicon substrate 602 can be restrained.

In this embodiment, the third inductor 304 and the fourth inductor 324are formed on the opposite face of the interconnect substrate 60 fromthe semiconductor chip 10 and the semiconductor chip 20. The thirdinductor 304 and the fourth inductor 324 are formed on an interconnectlayer 604 formed on the silicon substrate 602. The interconnect layer604 is a multilayer interconnect, and the third inductor 304 and thefourth inductor 324 are connected to each other through an interconnect(not shown) in the interconnect layer 604.

The first inductor 302 and the third inductor 304 constitute a firstsignal transmission element 300, and the second inductor 322 and thefourth inductor 324 constitute a second signal transmission element 320.As described above, the distance from the first inductor 302 to thethird inductor 304 differs from the distance from the second inductor322 to the fourth inductor 324.

More specifically, the first inductor 302 is formed in the multilayerinterconnect 400 of the semiconductor chip 10, and the second inductor322 is formed in the multilayer interconnect 500 of the semiconductorlayer 20. In each of the multilayer interconnects 400 and 500, two ormore insulating layers and two or more interconnect layers arealternately stacked, with an insulating layer being at the lowermostlayer. In this embodiment, the multilayer interconnect 400 has astructure that is formed by stacking an insulating layer 410, aninterconnect layer 412, an insulating layer 420, an interconnect layer422, an insulating layer 430, an interconnect layer 432, an insulatinglayer 440, and an interconnect layer 442 in this order. The multilayerinterconnect 500 has a structure that is formed by stacking aninsulating layer 510, an interconnect layer 512, an insulating layer520, an interconnect layer 522, an insulating layer 530, an interconnectlayer 532, an insulating layer 540, and an interconnect layer 542 inthis order. Each of the insulating layers may have a structure formed bystacking insulating films, or may be a single insulating film. Each ofthe multilayer interconnects 400 and 500 is covered with a protectionfilm (not shown). The number of layers in the multilayer interconnect400 and the number of layers in the multilayer interconnect 500 may bethe same as each other or differ from each other.

In the example illustrated in this drawing, the first inductor 302 isprovided in the interconnect layer 412 that is a first interconnectlayer of the multilayer interconnect 400, and the second inductor 322 isprovided in the interconnect layer 542 that is the uppermost layer ofthe multilayer interconnect 500.

The interconnect of each of the interconnect layers is a Cu interconnectformed by the damascene technique, and is buried in a groove formed ineach corresponding interconnect layer. Pads (not shown) are formed onthe interconnects of the uppermost layers. Alternatively, in themultilayer interconnects 400 and 500, at least one of the interconnectlayers may be an Al-alloy interconnect. The interconnects formed in theinterconnect layers are connected to one another through plugs buried inthe insulating layers.

Each of the insulating films forming the insulating layers and theinterconnect layers may be a SiO₂ film or a low-permittivity film.Low-permittivity films may be insulating films having relativepermittivity of 3.3 or lower, or more preferably, 2.9 or lower. Examplesof materials that can be used as the low-permittivity films include notonly SiOC but also polyhydrogen siloxane such as HSQ (hydrogensilsesquioxane), MSQ (methyl silsesquioxane), or MHSQ (methylatedhydrogen silsesquioxane), an aromatic-group-containing organic materialsuch as polyarylether (PAE), divinylsiloxane-bis-benzocyclobutene (BCB),or Silk (a registered trade name), SOG, FOX (flowable oxide) (aregistered trade name), CYTOP (a registered trade name), BCB(Benzocyclobutene), and the likes. Porous films of those substances mayalso be used as low-permittivity films.

Where the thickness of the multilayer interconnect 400 and the thicknessof the multilayer interconnect 500 differ from each other, theinterconnect substrate 60 might be slanted. In such a case, thebackgrinding amount of the first substrate 102 and the backgrindingamount of the second substrate 202 are changed so that the semiconductorchip 10 and the semiconductor chip 20 have the same thickness.

The first circuit 100 is a transmission circuit, and the second circuit200 is a reception circuit. Accordingly, the first inductor 302functions as a transmission-side inductor, and the third inductor 304functions as a reception-side inductor. Also, the fourth inductor 324functions as a transmission-side inductor, and the second inductor 322functions as a reception-side inductor.

For example, the first circuit 100 is a transmission-side driver circuit(such as a gate driver). The first circuit 100 amplifies a transmissionsignal formed by modulating a digital signal, and outputs the amplifiedsignal to the first inductor 302. For example, the second circuit 200 isa reception-side driver circuit (such as a gate driver). The secondcircuit 200 amplifies and then outputs a digital signal formed bymodulating a signal received by the second inductor 322.

The potentials of electric signals to be input to the first circuit 100and the second circuit 200 differ from each other. However, since thefirst signal transmission element 300 and the second signal transmissionelement 320 transmit electric signals by virtue of inductive coupling,no trouble occurs in the first circuit 100 and the second circuit 200.Where “the potentials of electric signals to be input differ from eachother” in the structure illustrated in FIG. 1, the amplitudes (thedifferences between the potential indicating “0” and the potentialindicating “1”) of the electric signals might differ from each other,the reference potentials (the potentials indicating “0”) of the electricsignals might differ from each other, the amplitudes of the electricsignals might differ from each other while the reference potentials ofthe electric signals differ from each other, or the like.

The first circuit 100 of the semiconductor chip 10 includes firsttransistors. The first transistors are an n-type transistor and a p-typetransistor. The n-type first transistor 121 is formed in a p-type well120, and includes two n-type impurity regions 124 to be the source anddrain, and a gate electrode 126. The p-type first transistor 141 isformed in an n-type well 140, and includes two p-type impurity regions144 to be the source and drain, and a gate electrode 146. A gateinsulating film is provided below each of the gate electrodes 126 and146. Those two gate insulating films have substantially the samethicknesses. The first transistors 121 and 141 constitute theabove-mentioned transmission-side driver circuit that is an inverter,for example.

A p-type impurity region 122 is formed in the well 120, and an n-typeimpurity region 142 is formed in the well 140. An interconnect forapplying the reference potential (the ground potential) of the n-typefirst transistor 121 is connected to the impurity region 122, and aninterconnect for applying the power-supply potential of the p-type firsttransistor 141 is connected to the impurity region 142.

The second circuit 200 of the semiconductor chip 20 includes secondtransistors. The second transistors are an n-type transistor and ap-type transistor. The n-type second transistor 221 is formed in ap-type well 220, and includes two n-type impurity regions 224 to be thesource and drain, and a gate electrode 226. The p-type second transistor241 is formed in an n-type well 240, and includes two p-type impurityregions 244 to be the source and drain, and a gate electrode 246. A gateinsulating film is provided below each of the gate electrodes 226 and246. The second transistors 221 and 241 constitute the above-mentionedreception-side driver circuit that is an inverter, for example.

A p-type impurity region 222 is formed in the well 220, and an n-typeimpurity region 242 is formed in the well 240. An interconnect forapplying the reference potential of the n-type second transistor 221 isconnected to the impurity region 222, and an interconnect for applyingthe power-supply potential of the p-type second transistor 241 isconnected to the impurity region 242.

In the example illustrated in this drawing, the gate insulating films ofthe first transistors 121 and 141 and the gate insulating films of thesecond transistors 221 and 241 have different thicknesses from eachother, but may have the same thicknesses.

The area of the interconnect substrate 60 is smaller than the sum of thearea of the semiconductor chip 10 and the area of the semiconductor chip20.

FIG. 3 is an equivalent circuit diagram of the semiconductor deviceshown in FIG. 1. The signals generated by the first circuit 100 arereceived by the second circuit 200 through the first signal transmissionelement 300 and the second signal transmission element 320. The firstsignal transmission element 300 transmits the signals by virtue of theinductive coupling between the first inductor 302 and the third inductor304. The second signal transmission element 320 transmits the signals byvirtue of the inductive coupling between the fourth inductor 324 and thesecond inductor 322.

Next, the functions and effects of this embodiment are described. Thepotentials of electric signals to be input to the first circuit 100 andthe second circuit 200 differ from each other. The breakdown voltagebetween the first circuit 100 and the second circuit 200 is determinedby the sum of the distance between the first inductor 302 and the thirdinductor 304, and the distance between the second inductor 322 and thefourth inductor 324. Therefore, the sum of the distance between thefirst inductor 302 and the third inductor 304, and the distance betweenthe second inductor 322 and the fourth inductor 324 needs to be equal toor larger than a certain value. When a semiconductor device is designed,the required value is divided between the distance from the firstinductor 302 to the third inductor 304 and the distance from the secondinductor 322 to the fourth inductor 324. The distance between the firstinductor 302 and the third inductor 304, and the distance between thesecond inductor 322 and the fourth inductor 324 differ from each other,and have appropriate values. With this arrangement, the efficiency insignal transmission from the first circuit 100 to the second circuit 200can be maximized. In this embodiment, the distance from the firstinductor 302 to the third inductor 304 differs from the distance fromthe second inductor 322 to the fourth inductor 324. Accordingly,insulation between the first circuit 100 and the second circuit 200 canbe secured while signals are being transferred with precision.

For example, since the first inductor 302 that is the transmission-sideinductor of the first signal transmission element 300 is connected tothe first circuit 100 that is a transmission circuit, a relatively largecurrent flows in the first inductor 302. On the other hand, since theinductive current flowing through the third inductor 304 that is thereception-side inductor of the first signal transmission element 300flows into the fourth inductor 324, a relatively small current flows inthe four inductor 324 that is the transmission-side inductor of thesecond signal transmission element 320. Therefore, a relatively largeinductive current is generated in the third inductor 304 that is thereception-side inductor of the first signal transmission element 300,and a relative small inductive current is generated in the secondinductor 322 that is the reception-side inductor of the second signaltransmission element 320. Accordingly, where the first inductor 302 isplaced in the interconnect layer 412 that is the lowermost layer of themultilayer interconnect 400, and the second inductor 322 is placed inthe uppermost interconnect layer of the multilayer interconnect 500 asin this embodiment, the signal transmission efficiency of the secondsignal transmission element 320 can be made higher while the breakdownvoltage in the first signal transmission element 300 is secured.

In this embodiment, the third inductor 304 is formed on the oppositeface of the interconnect substrate 60 from the semiconductor chip 10.Accordingly, the first inductor 302 and the third inductor 304 can beseparated farther away from each other so that the breakdown voltage ofthe first signal transmission element 300 can be made higher.

Also, when the substrate impurity density in the silicon substrate 602of the interconnect substrate 60 is made lower than the substrateimpurity density of the first substrate 102 and the substrate impuritydensity of the second substrate 202, generation of eddy current in thesilicon substrate 602 can be restrained by virtue of magnetic fieldsgenerated by the first signal transmission element 300 and the secondsignal transmission element 320.

Second Embodiment

FIG. 4 is a cross-sectional view showing the structure of asemiconductor device according to a second embodiment. FIG. 5 is aschematic plan view of the semiconductor device shown in FIG. 4. FIG. 4is a cross-sectional view of the semiconductor device, taken along theline B-B′ of FIG. 5. This semiconductor device has the same structure asthe semiconductor device according to the first embodiment, except thatthe third inductor 304 and the fourth inductor 324 are formed on theface of the interconnect substrate 60 that faces the semiconductor chip10 and the semiconductor chip 20.

According to this embodiment, insulation between the first circuit 100and the second circuit 200 can also be secured while signals are beingtransferred with precision. Further, the fourth inductor 324 is formedon the face of the interconnect substrate 60 facing the semiconductorchip 20. With this arrangement, the distance between the fourth inductor324 and the second inductor 322 is shortened, and the signaltransmission efficiency of the second signal transmission element 320can be made higher accordingly.

Third Embodiment

FIG. 6 is a schematic cross-sectional view showing the structure of asemiconductor device according to a third embodiment. FIG. 7 is aschematic plan view of the semiconductor device shown in FIG. 6. FIG. 6is a cross-sectional view of the semiconductor device, taken along theline C-C′ of FIG. 7. This semiconductor device has the same structure asthe semiconductor device according to the first embodiment, except thata transmission/reception circuit 606 is formed in the face of thesilicon substrate 602 having the interconnect layer 604 formed thereon.

FIG. 8 is an equivalent circuit diagram of the semiconductor deviceshown in FIGS. 6 and 7. The transmission/reception circuit 606 isprovided between the third inductor 304 and the fourth inductor 324 inthe circuit diagram. The transmission/reception circuit 606 includes areception circuit and a transmission circuit. After demodulating asignal received by the third inductor 304 from the first inductor 302,the transmission/reception circuit 606 re-modulates the signal andoutputs the re-modulated signal to the fourth inductor 324. Although thetransmission/reception circuit 606 shown in FIG. 6 is formed in the faceof the interconnect substrate 60 having the interconnect layer 604formed thereon, the transmission/reception circuit 606 may be formed inthe opposite face from the face on which the interconnect layer 604 isformed.

This embodiment can achieve the same effects as those of the first orsecond embodiment. Furthermore, after demodulating a signal received bythe third inductor 304 from the first inductor 302, thetransmission/reception circuit 606 re-modulates the signal and outputsthe re-modulated signal to the fourth inductor 324. Accordingly, thesignal transmission efficiency is made even higher.

Fourth Embodiment

FIG. 9 is a schematic cross-sectional view showing the structure of asemiconductor device according to a fourth embodiment. FIG. 10 is aschematic plan view of the semiconductor device shown in FIG. 9. FIG. 9is a cross-sectional view of the semiconductor device, taken along theline D-D′ of FIG. 10. This semiconductor device has the same structureas one of the semiconductor devices according to the first through thirdembodiments, except that first circuit 100 and the first inductor 302are formed in the first region 12 of the semiconductor chip 10, and thesecond circuit 200 and the second inductor 322 are formed in the secondregion 14 of the semiconductor chip 10. FIGS. 9 and 10 illustrate thesame situation as that in the third embodiment.

The first substrate 102 is a SOI (Silicon On Insulator) substrate, andhas a structure having an insulating layer 106 and a silicon layer 108stacked in this order on a silicon substrate 104. A dielectric isolationlayer 109 that insulates the first region 12 and the second region 14from each other is buried in the silicon layer 108. The lower end of thedielectric isolation layer 109 reaches the insulating layer 106.

According to this embodiment, the same effects as those of any of thefirst through third embodiments can also be achieved. Furthermore, thefirst circuit 100 as a transmission circuit and the second circuit 200as a reception circuit may be formed in the semiconductor chip 10.

Although embodiments of the present invention have been described so farwith reference to the accompanying drawings, those embodiments aremerely examples of the present invention, and various structures otherthan the above described ones may be employed.

It is apparent that the present invention is not limited to the aboveembodiment, but may be modified and changed without departing from thescope and spirit of the invention.

1. A semiconductor device comprising: one or two semiconductor chipsthat include an interconnect layer; and an interconnect substrate thatis attached to an interconnect layer side of said one or twosemiconductor chips, wherein said one or two semiconductor chipsincludes: a first circuit that generates a signal; a first inductor thatis formed in said interconnect layer and is connected to said firstcircuit; a second circuit that processes said signal; and a secondinductor that is formed in said interconnect layer and is connected tosaid second circuit, said interconnect substrate includes: a thirdinductor that is located above said first inductor; and a fourthinductor that is located above said second inductor and is connected tosaid third inductor, and a distance from said first inductor to saidthird inductor differs from a distance from said second inductor to saidfourth inductor.
 2. The semiconductor device according to claim 1,wherein said distance from said first inductor to said third inductor islonger than said distance from said second inductor to said fourthinductor.
 3. The semiconductor device according to claim 1, wherein saidinterconnect substrate is formed with a silicon substrate.
 4. Thesemiconductor device according to claim 3, wherein said one or twosemiconductor chips are formed with a silicon substrate, and saidinterconnect substrate has a lower substrate impurity density than asubstrate impurity density of said one or two semiconductor chips. 5.The semiconductor device according to claim 3, further comprising atransmission/reception circuit that is formed in said interconnectsubstrate and is provided between said third inductor and said fourthinductor in a circuit diagram.
 6. The semiconductor device according toclaim 1, wherein said third inductor and said fourth inductor are formedon a face of said interconnect substrate, said face being on theopposite side from said one or two semiconductor chips.
 7. Thesemiconductor device according to claim 1, wherein said first circuitand said first inductor are formed in a first one of said semiconductorchips, said second circuit and said second inductor are formed in asecond one of said semiconductor chips, and said interconnect substrateis placed over said first semiconductor chip and said secondsemiconductor chip.
 8. The semiconductor device according to claim 1,wherein said first circuit, said second circuit, said first inductor,and said second inductor are formed in one of said semiconductor chips,said first circuit and said first inductor are formed in a first regionof said semiconductor chip, said second circuit and said second inductorare formed in a second region of said semiconductor chip, and said firstregion and said second region are insulated from each other.